Midazolam has been shown to have powerful effects similar to steroid epidurally, but there are concerns about its perservative. However, it is the same Benzyl alcohol preservative seen in Kenalog which is widely used in epidural injections. Recent animal vitreous injections of benzyl alcohol have found 0.071% benzyl alcohol does not cause retinal toxicity – easily achieve with IV Versed if given caudally in 15 mls dilutant that has some bicarbonate to ph balance the formulation. Even then, that does not consider that the solution will be diluted even more caudally.
Recent study found Epidural Midazolam Effective in Chronic Back Pains – especially post laminectomy
Pain Med. 2011 Sep;12(9):1309-15.
Intrathecal midazolam as supplementary analgesia for chronic lumbar pain–15 years’ experience.
Prochazka J, Hejcl A, Prochazkova L. abstract here
- dose of midazolam was dissolved in 5% glucose or in normal saline up to 3 mL in volume – I prefer D5W as it has been shown to have mild analgesic properties (neuroprolotherapy) and there will be salt added when 8.4% sterile sodium bicabonate 1 ml added to ph balance the otherwise ph 3.3% solution – (note: will turn turbid like kenalog is) – present author did not ph balance.
- They gave their doses into spinal fluid space – intrathecally – in 3 ml
- They started with 2 mg and worked up to 5 mg – using 5 mg/ml Versed IV would mean starting with 0.4 ml and working up to 1 ml.
- Doses were repeated monthly
- “in more than 65% of the cases, we achieved a significant pain reduction lasting more than 4 weeks”
- Doses used:
- I’ve had anesthetists express concerns re the preservatives used in IV midazolam – but it is the same benzyl alcohol used in Kenalog which they widely use.
It has been shown that 0.071% Benzyl alcohol is non-toxic to rabbit retina:
Invest. Ophthalmol. Vis. Sci. January 2007 vol. 48 no. 1 390-395
Long-term Retinal Toxicity of Intravitreal Commercially Available Preserved Triamcinolone Acetonide (Kenalog) in Rabbit Eyes
Thomas A. Albini, Muhammad M. Abd-El-Barr, Petros E. Carvounis, Mohan N. Iyer, Rohit R. Lakhanpal, Mark E. Pennesi, Patricia Chevez-Barrios, Samuel M. Wu and Eric R. Holz
free article here
- “The preponderance of data in the study by Dierks et al.12 and in our study seem to support the conclusion that IVTK injection achieving an intravitreal benzyl alcohol concentration of 0.071% (0.1 mL of 0.99 mg/mL benzyl alcohol in 1.4 mL rabbit vitreous) does not cause diffuse retinal toxicity”
- That concentration can be achieved by diluting Versed 5 mg/ml with 1 ml 8.4% sodium bicabonate and 13 mls D5W to make 15 mls and give it caudally. That 0.07% would be diluted even further caudally.
- For those who wish no preservative, mix IV midazolam with twice the amount of 8.4 % sodium bicarbonate in a sterile red vacutainer, spin down the precipitate (not soluble at neutral ph), gently remove supernatant and reconstitute suspension in D5W .
- When given, I have a family member or staff stay with patient. Oxymetry is monitored in case subject gets drowsy though author states that is uncommon. If drowsiness ensues, it usually only last 1/2 hour. Just a practical note – if patient could cut down or avoid AM opioids and any other sedating meds until after injection, then sedation would be less.
Comment – I feel this is an option for steroid epidurals that have worn off between their scheduled doses.